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    <meta charset="UTF-8">
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    <title>Document</title>
    <style>
        * {
            padding: 0;
            margin: 0;
            list-style: none;
        }
        a{
            text-decoration: none;
        }
        p{
            height: 800px;
        }
        div{
            width: 100vw;
            height: 80px;
            background-color: rgba(0 , 0, 0, .8);
            position: fixed;
            bottom: -75px;
            color: #fff;
            padding: 20px;
            box-sizing: border-box;
            transition: bottom .5s linear;
        }
        div:hover{
            bottom: 0px;
        }
    </style>

</head>

<body>
    <p>

    </p>
    <div>
        今天端午节竟然不放假，也太开心了吧，我们能多学两天的知识！！！
    </div>
</body>

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